The electronics industry has experienced an ever increasing demand for smaller and faster electronic devices which are simultaneously able to support a greater number of increasingly complex and sophisticated functions. Accordingly, there is a continuing trend in the semiconductor industry to manufacture low-cost, high-performance, and low-power integrated circuits (ICs). Thus far these goals have been achieved in large part by scaling down semiconductor IC dimensions (e.g., minimum feature size) and thereby improving production efficiency and lowering associated costs. However, such scaling has also introduced increased complexity to the semiconductor manufacturing process. Thus, the realization of continued advances in semiconductor ICs and devices calls for similar advances in semiconductor manufacturing processes and technology.
In particular, the scaling down of IC dimensions has considerably increased the challenges associated with finding defects using existing wafer inspection methods. Wafer inspection may be subdivided into two primary technologies—optical inspection and electron beam (e-beam) inspection. While optical inspection has been a semiconductor wafer inspection workhorse for many years, e-beam inspection has gained considerable interest, particularly for its ability to detect smaller defects than those which can be detected using optical inspection. For example, e-beam inspection may provide detection of defects down to about 3 nanometers (nm), whereas optical inspection may begin to have trouble finding defects smaller than 30 nm. E-beam inspection may also be used to detect voltage-contrast type defects, such as electrical shorts or opens at a contact or an interconnect void. The benefits of e-beam inspection are evident, but there remain challenges. For example, at least some existing e-beam inspection methods suffer from low inspection sensitivity, low throughput, and/or long analysis cycle time. Thus, existing techniques have not proved entirely satisfactory in all respects.